1. Field of the Invention
The present invention relates to a method for operating a computer system to perform date operations, and more particularly, to a method for operating a computer system to accurately perform date operations spanning centuries.
2. Description of the Related Art
Most existing computer application software treats a date in a format similar to “MM/DD/YY” or “YY/DDD,” using 2 digits of a 4 digit year number, resulting in 2 digit year numbers. For example, the year 1998 is input, stored, processed and displayed as “98”. However, starting at the year 2000, this treatment will cause problems because “00” could be interpreted as either “1900” or “2000,” and, for example, the length of a period from 1998 to 2000 could be negative if 98 is subtracted from 2000. This problem is known as the “Year 2000 (Y2K) Problem” in the industry, and has been considered a crisis.
Several inventions attempt to solve the Y2K problem by providing complex and expensive computer programs. A discussion of related, representative art follows.
One such invention is described in U.S. Pat. No. 5,289,393 which issued to S. Kaya on Feb. 22, 1994. This invention is a portable electronic apparatus having a calendar feature which stores the year in 4 digits.
U.S. Pat. No. 5,600,836 which issued to H. Alter on Feb. 4, 1997, discloses a system and method for processing date-dependent information which spans one or two centuries. The invention includes time change interfaces that convert date data from local time to zone time so that all of the dates are in one century, as well as a method of converting from zone time back to local time.
U.S. Pat. No. 5,630,118 which issued to D. P. Shaughnessy on May 13, 1997, discloses a system and method for modifying and operating a computer system to perform date operations on date fields spanning centuries. The system comprises a subroutine that determines which dates within the program correspond to specified date criteria and performs a date operation on the date field.
U.S. Pat. No. 5,644,762 which issued to T. B. Soeder on May 14, 1996, discloses a method and apparatus for recording and reading date data having coexisting formats. The invention uses a system whereby years past 1999 are stored as binary integers in fields previously reserved for representations of years as two decimal digits, so that the last two decimal digits will be able to coexist for at least ten thousand years.
U.S. Pat. No. 5,668,989 which issued to D. Mao on Sep. 16, 1997, discloses a system employing two-digit hybrid radix year numbers for the year 2000 and beyond. This system treats the higher digit as hexadecimal, but displays the digit in a decimal-like style, while the lower digit is treated as ordinary decimal, so that the year 1900 is represented by 00 and the year 2000 is represented as '00.
British Patent No. 2,312,536 which was published on Oct. 29, 1997 and issued to Anderson et al., discloses a method and apparatus for identifying and correcting date errors. The invention consists of a suite of computer programs used together to detect and correct year 2000 problems in a personal computer. One aspect of the invention involves the correcting the century value of the date operations a computer when the computer rolls over to the year 2000.
Lastly, The Year 2000 and 2-Digit Dates: A Guide for Planning and Implementation, 3d ed., published by IBM in May, 1996, discloses three solutions and techniques for solving “Y2K” problems. The first technique involves conversion to full 4-digit year formats (DDDD) from 2-digit year (DD) formats, the second technique involves windowing techniques, namely, externalizing 2-digit or 4-digit year formats, and the third technique involves using a 2-digit encoding/compression scheme, whereby 4-digit year data are compressed into 2-digit existing space.
None of the above inventions and patents, taken either singularly or in combination, is seen to describe the instant invention as claimed. Thus, a date formatting system solving the aforementioned problems is desired.